[INFO] fetching crate fallible_vec 0.3.1...
[INFO] testing fallible_vec-0.3.1 against beta-2025-09-21 for beta-1.91-3
[INFO] extracting crate fallible_vec 0.3.1 into /workspace/builds/worker-2-tc2/source
[INFO] started tweaking crates.io crate fallible_vec 0.3.1
[INFO] finished tweaking crates.io crate fallible_vec 0.3.1
[INFO] tweaked toml for crates.io crate fallible_vec 0.3.1 written to /workspace/builds/worker-2-tc2/source/Cargo.toml
[INFO] validating manifest of crates.io crate fallible_vec 0.3.1 on toolchain beta-2025-09-21
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2025-09-21" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2025-09-21" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]      Locking 1 package to latest compatible version
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2025-09-21" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:e90291280db7d1fac5b66fc6dad9f9662629e7365a55743daf9bdf73ebc4ea79" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2025-09-21" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] a802f511f27d2f667002f0d7969f828e828e87dc59ecceaf8ff993907cbc1ef8
[INFO] running `Command { std: "docker" "start" "-a" "a802f511f27d2f667002f0d7969f828e828e87dc59ecceaf8ff993907cbc1ef8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "a802f511f27d2f667002f0d7969f828e828e87dc59ecceaf8ff993907cbc1ef8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "a802f511f27d2f667002f0d7969f828e828e87dc59ecceaf8ff993907cbc1ef8", kill_on_drop: false }`
[INFO] [stdout] a802f511f27d2f667002f0d7969f828e828e87dc59ecceaf8ff993907cbc1ef8
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=warn" "-e" "RUSTDOCFLAGS=--cap-lints=warn" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:e90291280db7d1fac5b66fc6dad9f9662629e7365a55743daf9bdf73ebc4ea79" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2025-09-21" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] ab9edca0cd18a782b3ddbf47dc9a939bec79bd73af7acdd3a0629bd3593495bf
[INFO] running `Command { std: "docker" "start" "-a" "ab9edca0cd18a782b3ddbf47dc9a939bec79bd73af7acdd3a0629bd3593495bf", kill_on_drop: false }`
[INFO] [stderr]    Compiling fallible_vec v0.3.1 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]   --> src/lib.rs:50:40
[INFO] [stdout]    |
[INFO] [stdout] 50 | #![cfg_attr(feature = "allocator_api", feature(allocator_api))]
[INFO] [stdout]    |                                        ^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]   --> src/lib.rs:51:44
[INFO] [stdout]    |
[INFO] [stdout] 51 | #![cfg_attr(feature = "use_unstable_apis", feature(slice_range, try_reserve_kind))]
[INFO] [stdout]    |                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `fallible_vec` (lib) due to 2 previous errors
[INFO] running `Command { std: "docker" "inspect" "ab9edca0cd18a782b3ddbf47dc9a939bec79bd73af7acdd3a0629bd3593495bf", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "ab9edca0cd18a782b3ddbf47dc9a939bec79bd73af7acdd3a0629bd3593495bf", kill_on_drop: false }`
[INFO] [stdout] ab9edca0cd18a782b3ddbf47dc9a939bec79bd73af7acdd3a0629bd3593495bf